Re: [kvm-unit-tests PATCH v1 1/4] lib: s390x: add support for SCLP console read

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On 11/04/2022 12.07, Nico Boehr wrote:
Add a basic implementation for reading from the SCLP ACII console. The goal of

s/ACII/ASCII/

this is to support migration tests on s390x. To know when the migration has been
finished, we need to listen for a newline on our console.

Hence, this implementation is focused on the SCLP ASCII console of QEMU and
currently won't work under e.g. LPAR.

Signed-off-by: Nico Boehr <nrb@xxxxxxxxxxxxx>
---
  lib/s390x/sclp-console.c | 81 +++++++++++++++++++++++++++++++++++++---
  lib/s390x/sclp.h         |  7 ++++
  s390x/Makefile           |  1 +
  3 files changed, 83 insertions(+), 6 deletions(-)

diff --git a/lib/s390x/sclp-console.c b/lib/s390x/sclp-console.c
index fa36a6a42381..8e22660bf25d 100644
--- a/lib/s390x/sclp-console.c
+++ b/lib/s390x/sclp-console.c
@@ -89,6 +89,10 @@ static char lm_buff[120];
  static unsigned char lm_buff_off;
  static struct spinlock lm_buff_lock;
+static char read_buf[4096];
+static int read_index = sizeof(read_buf) - 1;
+static int read_buf_end = 0;
+
  static void sclp_print_ascii(const char *str)
  {
  	int len = strlen(str);
@@ -185,7 +189,7 @@ static void sclp_print_lm(const char *str)
   * indicating which messages the control program (we) want(s) to
   * send/receive.
   */
-static void sclp_set_write_mask(void)
+static void sclp_write_event_mask(int receive_mask, int send_mask)
  {
  	WriteEventMask *sccb = (void *)_sccb;
@@ -195,18 +199,27 @@ static void sclp_set_write_mask(void)
  	sccb->h.function_code = SCLP_FC_NORMAL_WRITE;
  	sccb->mask_length = sizeof(sccb_mask_t);
- /* For now we don't process sclp input. */
-	sccb->cp_receive_mask = 0;
-	/* We send ASCII and line mode. */
-	sccb->cp_send_mask = SCLP_EVENT_MASK_MSG_ASCII | SCLP_EVENT_MASK_MSG;
+	sccb->cp_receive_mask = receive_mask;
+	sccb->cp_send_mask = send_mask;
sclp_service_call(SCLP_CMD_WRITE_EVENT_MASK, sccb);
  	assert(sccb->h.response_code == SCLP_RC_NORMAL_COMPLETION);
  }
+static void sclp_console_enable_read(void)
+{
+	sclp_write_event_mask(SCLP_EVENT_MASK_MSG_ASCII, SCLP_EVENT_MASK_MSG_ASCII | SCLP_EVENT_MASK_MSG);
+}
+
+static void sclp_console_disable_read(void)
+{
+	sclp_write_event_mask(0, SCLP_EVENT_MASK_MSG_ASCII | SCLP_EVENT_MASK_MSG);
+}
+
  void sclp_console_setup(void)
  {
-	sclp_set_write_mask();
+	/* We send ASCII and line mode. */
+	sclp_write_event_mask(0, SCLP_EVENT_MASK_MSG_ASCII | SCLP_EVENT_MASK_MSG);
  }
void sclp_print(const char *str)
@@ -227,3 +240,59 @@ void sclp_print(const char *str)
  	sclp_print_ascii(str);
  	sclp_print_lm(str);
  }
+
+#define SCLP_EVENT_ASCII_DATA_STREAM_FOLLOWS 0
+
+static int console_refill_read_buffer(void)
+{
+	const int MAX_EVENT_BUFFER_LEN = SCCB_SIZE - offsetof(ReadEventDataAsciiConsole, ebh);
+	ReadEventDataAsciiConsole *sccb = (void *)_sccb;
+	const int EVENT_BUFFER_ASCII_RECV_HEADER_LEN = sizeof(sccb->ebh) + sizeof(sccb->type);
+	int ret = -1;
+
+	sclp_console_enable_read();
+
+	sclp_mark_busy();
+	memset(sccb, 0, 4096);
+	sccb->h.length = PAGE_SIZE;
+	sccb->h.function_code = SCLP_UNCONDITIONAL_READ;
+	sccb->h.control_mask[2] = 0x80;

Add at least a comment about what the 0x80 means, please?

+
+	sclp_service_call(SCLP_CMD_READ_EVENT_DATA, sccb);
+
+	if ((sccb->h.response_code == SCLP_RC_NO_EVENT_BUFFERS_STORED) ||
+	    (sccb->ebh.type != SCLP_EVENT_ASCII_CONSOLE_DATA) ||
+	    (sccb->type != SCLP_EVENT_ASCII_DATA_STREAM_FOLLOWS)) {
+		ret = -1;
+		goto out;
+	}
+
+	assert(sccb->ebh.length <= MAX_EVENT_BUFFER_LEN);
+	assert(sccb->ebh.length > EVENT_BUFFER_ASCII_RECV_HEADER_LEN);
+
+	read_buf_end = sccb->ebh.length - EVENT_BUFFER_ASCII_RECV_HEADER_LEN;
+
+	assert(read_buf_end <= sizeof(read_buf));
+	memcpy(read_buf, sccb->data, read_buf_end);
+
+	read_index = 0;

Set "ret = 0" here?

+out:
+	sclp_console_disable_read();
+
+	return ret;
+}
+
+int __getchar(void)
+{
+	int ret;
+
+	if (read_index >= read_buf_end) {
+		ret = console_refill_read_buffer();
+		if (ret < 0) {
+			return ret;
+		}
+	}
+
+	return read_buf[read_index++];
+}

 Thomas




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